A light emitting diode, namely, an LED, is commonly used as a light source for an image projecting apparatus, or namely a projector, because of its properties of reduced power consumption and heat release, decreased dimensions, and extended lifetime, as will be described below.
A downsized imaging apparatus has been proposed which is provided with an illumination apparatus consisting of light source of a plurality of low power light emitting elements, an illumination uniformizing means for making beams from the light source homogenous to overlap them onto a light valve, and a polarization converter converting light from the light source in polarization phase suitable to the light valve to raise efficiency of the illumination apparatus, where the illumination apparatus is used along with a projection means to direct rays of three primary colors at the screen (see Patent Document 1).
Another LED light projector is a projector display apparatus having a light source, a light modulator modulating light from the light source, and a projection lens projecting modulated incident light from the light modulator, where the light source is of light emitting elements deployed in arrays, and a light diffusing means is provided to direct beams emitted individually from the light emitting elements throughout the light modulation region on the light modulator (see Patent Document 2).
Still another LED light projector is an image projector that includes a dichroic prism synthesizes trichromatic rays of red, green, and blue emitted from light emitting diodes to illuminate a liquid crystal light valve, and that also includes polarized beam irradiating elements that make beams from the light emitting diodes homogeneous in polarization to illumine the liquid crystal light valve, and the polarized beam irradiating elements function as a polarizer to uniformize polarized incident light upon a polarized beam splitter, namely, upon the liquid crystal light valve, and also as an emitted light analyzer, thereby enabling a projection lens to direct the beams modulated on the liquid crystal light valve at the screen (see Patent Document 3).